The present invention generally relates to computer apparatus, and, in a preferred embodiment thereof, more particularly relates to the EMI/RFI shielding of personal computers.
Various operating components of a personal computer, such as its central processing unit, memory structures and the like, are typically mounted on a side of a printed circuit board supported in the plastic housing of the computer in a spaced, parallel relationship with an exterior wall of the housing, with the components facing the interior side surface of the housing wall. Since this plastic wall is essentially transparent to EMI/RFI radiation generated by the components during computer operation, it is necessary to incorporate some type of EMI shielding into the computer to at least minimize, if not completely eliminate, the generation of EMI/RFI radiation outwardly through the computer housing.
This requisite EMI shielding of the computer has conventionally been accomplished by coating the computer housing with a metallic material which reflects the generated EMI/RFI radiation and traps it in the housing. One conventionally utilized method of metallically coating the housing is to electrochemically cover it with, for example, a nickel-based coating. Another conventionally utilized method is to paint the housing with, for example, a copper-based paint.
While at first glance these and other conventional methods of forming an EMI shielding structure directly on the plastic computer housing appear to be relatively simple, straightforward solutions to the shielding requirement, they are subject to several well known problems, limitations and disadvantages. For example, the metallic coating of the plastic computer housing materially increases the overall fabrication cost of the computer. Moreover, the metallic coating is susceptible to being scratched or otherwise marred during the fabrication process. When this occurs it is typically necessary to scrap the housing portion which has been scratched or marred. Additionally, while the metallic coating of the housing substantially prevents outward transmission of EMI/RFI radiation through the housing walls, it does not materially inhibit such outward generation through the various housing joints and openings necessarily present in the housing.
In view of the foregoing it can readily be seen that a need exists for improved apparatus and methods for providing EMI/RFI shielding for a computer. It is accordingly an object of the present invention to provide such improved apparatus and methods.